Re: [Xen-devel] Time Skewing on Windows XP

[Suravee Suthikulanit <suravee.suthikulpanit@xxxxxxx>]

On 3/14/2013 11:06 AM, Jan Beulich wrote:
> > > > On 14.03.13 at 16:16, Suravee Suthikulanit<suravee.suthikulpanit@xxxxxxx>  
> > > > wrote:
> > I finally traced the issue back to the patch that this first happened.  This
> > bug started in the patch :
> >
> > H86/HVM: assorted RTC emulation adjustment (w/ git commit id
> > 620d5dad54008e40798c4a0c4322aef274c36fa3)
> >
> > I believe there are some issues with the changes in rtc_ioport_read in the
> > arch/x86/hvm/rtc.c and in the pt_update_irq().
> One thing you may want to try is remove the call from REG_C
> read to rtc_timer_update() again - on a second thought it may
> be wrong to do it here, as (other than check_update_timer()
> and alarm_timer_update()) the function doesn't change with
> RTC_PF getting cleared (i.e. I may have wrongly added the call
> in analogy to the other two).
If I do the followings, things start working again:
1. remove the rtc_timer_update() in the rtc_ioport_read()
2. Revert back the "rtc_periodic_cb()" and remove the 
"rtc_periodic_interrupt()"
What was the purpose of changing the "rtc_periodic_cb()" to 
"rtc_periodic_interrupt()" ?
Suravee
> I would expect the issue to be that create_periodic_time()
> pointlessly destroys and then recreates an identical rate timer.
>
> I'm puzzled though that some Windows versions depend on
> the RTC to maintain their wall clock time...
>
> Jan


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